It is customary to form geometric modeling kits or units comprised of universal nodes or connectors which can be expanded into structural networks by the interconnection of nodes with connecting struts or spokes. Typically, the struts are elongated with each end being insertable into a selected opening or cavity in a node and, by combining a series of nodes and struts together in different selected angular relationships, numerous three-dimensional figures can be constructed. Such systems or kits have definite aesthetic and structural appeal both from the standpoint of providing a geometric modeling kit or toy for persons of all ages as well as rather sophisticated geometric structural systems. Representative of such approaches is that disclosed in U.S. Pat. No. 3,600,825 to P. J. Pearce in which the nodes themselves are made up of radially extending spokes of different cross-sectional configurations which are interconnected together by struts and splice members. The spokes and struts are both shape-coded and in some cases color-coded to facilitate matching up or interconnection of ends of corresponding cross section, as further aided by the use of coupling members therebetween. Again, however, the node itself is a star-like rigid molded or fabricated device having spokes of various cross-sectional configurations radiating from a common center.
Another approach is exemplified by U.S. Pat. No. 3,722,153. Baer in which a structural network or three-dimensional figure is formed by connection of hall-shaped nodes or connectors and structs into different geometric configurations utilizing the five-fold symmetries of the icosahedron and the dodecanedron. The structural elements must be attached, such as, by welding their ends at different angles to the geometric connectors or nodes to define the different angles of the structural network but without the benefit of shape-coding between the respective nodes and struts.
In the past, construction of the nodes as employed in the Pearce and Baer patents has presented insurmountable problems in terms of one-piece, high strength construction. The nodes of Baer were designed to be essentially of spherical construction, and the geometry of the ball-shaped connectors as employed in Baer or the radiating spokes as employed in Pearce virtually precluded one-piece construction or molding.
It is therefore proposed to provide a geometric structural system having particular application to modeling kits or toys in which the nodes or connectors can be formed of one-piece construction to lend the desired strength and unity to the system while at the same time achieve by means of shape-coding and color-coding where desired the proper matching or interrelationship between the connecting struts or structural elements in the formation of different geometrical designs.
Other U.S. Letters Patent of interest are those to U.S. Pat. No. 3,341,989 to D. G. Emmerich; U.S. Pat. No. 3,510,962 to L. Sato; U.S. Pat. No. 3,854,255 to R. L. Baker; U.S. Pat. No. 4,258,513 to H. Bergman; U.S. Pat. No. 4,271,628 to J. V. Barlow; and U.S. Pat. Nos. 4,326,354 and 4,348,830 to C. E. Haberg; also, French Pat. No. 1,425,234 to M. Marboeuf.